On the Origin of Species. Sixth Edition

First published in 1859 and revised through six editions in response to two decades of scientific debate, On the Origin of Species laid out the theory of evolution by natural selection with a wealth of evidence drawn from geology, breeding, and comparative anatomy. This sixth and final edition, incorporating Darwin's fullest replies to his critics, remains the definitive text of the single most influential scientific work of the nineteenth century - the foundation of modern biology.